[PATCH 11/14] iomap: Support THP writeback

Matthew Wilcox (Oracle)
2020-10-14T09:30:27Z

Use offset_in_thp() and similar helpers to submit THPs for writeback.
This simplifies the logic in iomap_do_writepage() around handling the
end of the file.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
fs/iomap/buffered-io.c | 30 +++++++++++++++---------------
1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 0a1fe7d1a27c..38fd69ebd4cc 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1394,7 +1394,7 @@ iomap_add_to_ioend(struct inode *inode, loff_t offset, struct page *page,
{
sector_t sector = iomap_sector(&wpc->iomap, offset);
unsigned len = i_blocksize(inode);
- unsigned poff = offset & (PAGE_SIZE - 1);
+ unsigned poff = offset_in_thp(page, offset);
bool merged, same_page = false;

if (!wpc->ioend || !iomap_can_add_to_ioend(wpc, offset, sector)) {
@@ -1444,8 +1444,9 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
struct iomap_page *iop = iomap_page_create(inode, page);
struct iomap_ioend *ioend, *next;
unsigned len = i_blocksize(inode);
- u64 file_offset; /* file offset of page */
+ loff_t pos;
int error = 0, count = 0, i;
+ int nr_blocks = i_blocks_per_page(inode, page);
LIST_HEAD(submit_list);

WARN_ON_ONCE(iop && atomic_read(&iop->write_bytes_pending) != 0);
@@ -1455,20 +1456,20 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
* end of the current map or find the current map invalid, grab a new
* one.
*/
- for (i = 0, file_offset = page_offset(page);
- i < (PAGE_SIZE >> inode->i_blkbits) && file_offset < end_offset;
- i++, file_offset += len) {
+ for (i = 0, pos = page_offset(page);
+ i < nr_blocks && pos < end_offset;
+ i++, pos += len) {
if (iop && !test_bit(i, iop->uptodate))
continue;

- error = wpc->ops->map_blocks(wpc, inode, file_offset);
+ error = wpc->ops->map_blocks(wpc, inode, pos);
if (error)
break;
if (WARN_ON_ONCE(wpc->iomap.type == IOMAP_INLINE))
continue;
if (wpc->iomap.type == IOMAP_HOLE)
continue;
- iomap_add_to_ioend(inode, file_offset, page, iop, wpc, wbc,
+ iomap_add_to_ioend(inode, pos, page, iop, wpc, wbc,
&submit_list);
count++;
}
@@ -1549,11 +1550,11 @@ iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data)
{
struct iomap_writepage_ctx *wpc = data;
struct inode *inode = page->mapping->host;
- pgoff_t end_index;
u64 end_offset;
loff_t offset;

- trace_iomap_writepage(inode, page_offset(page), PAGE_SIZE);
+ VM_BUG_ON_PGFLAGS(PageTail(page), page);
+ trace_iomap_writepage(inode, page_offset(page), thp_size(page));

/*
* Refuse to write the page out if we are called from reclaim context.
@@ -1590,10 +1591,8 @@ iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data)
* ---------------------------------^------------------|
*/
offset = i_size_read(inode);
- end_index = offset >> PAGE_SHIFT;
- if (page->index < end_index)
- end_offset = (loff_t)(page->index + 1) << PAGE_SHIFT;
- else {
+ end_offset = page_offset(page) + thp_size(page);
+ if (end_offset > offset) {
/*
* Check whether the page to write out is beyond or straddles
* i_size or not.
@@ -1605,7 +1604,8 @@ iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data)
* | | Straddles |
* ---------------------------------^-----------|--------|
*/
- unsigned offset_into_page = offset & (PAGE_SIZE - 1);
+ unsigned offset_into_page = offset_in_thp(page, offset);
+ pgoff_t end_index = offset >> PAGE_SHIFT;

/*
* Skip the page if it is fully outside i_size, e.g. due to a
@@ -1636,7 +1636,7 @@ iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data)
* memory is zeroed when mapped, and writes to that region are
* not written out to the file."
*/
- zero_user_segment(page, offset_into_page, PAGE_SIZE);
+ zero_user_segment(page, offset_into_page, thp_size(page));

/* Adjust the end_offset to the end of file */
end_offset = offset;
--
2.28.0